Will Bisset, who is a pet food researcher and expert nutritionist at UK ethical retailer Pets Corner, said: “Whilst it might be tempting to feed pets with human treats, many of them contain poisonous and life threatening chemicals that can either seriously harm or kill animals.

“For example, onion in any form, particularly the powder that is commonly found in most savoury foods including crisps, pizza and many sauces, contains disulphides and thiosulphates that are extremely poisonous to dogs, and even more so for cats, causing anaemia and damaging red blood cells.

“Likewise, toxins found in grapes and raisins, as well as chocolate, can also cause severe damage to a pet’s health.”

Will continued: “Artificial sugar substitutes, such as Xylitol, can be really harmful to pets, and corn syrup should be avoided at all costs.”

Earlier in the year, the pet retailer warned customers of the common misconception that lettuce and carrots – both of which can result in serious side effects - are safe for rabbits to consume.

Lucy Ross, Head of Training at Pets Corner, said: “The bulk of a rabbit’s diet should be made up of hay with 10 per cent of what they eat comprising vegetables such as curly kale, courgette, cabbage or cauliflower leaves.

“The good news is there is one festive favourite rabbits can enjoy safely and that’s Brussels sprouts.”

Whilst nuts are a traditional human treat at Christmas, many of them including almonds, walnuts, hickory nuts, macadamias, pecans and pistachios are toxic to cats and dogs and can cause intestinal obstructions. And even though apple flesh is a perfectly safe ingredient often included in many holistic dog foods, the seeds themselves contain a natural chemical that releases cyanide when digested by animals and are potentially lethal.

Will added: “Although there are many human foods that are safe to feed, it’s always better to provide a high quality food for pets that provides them with all the nutritional qualities and quantities they need.

“Pet owners should be wary of feeding human foods in any form to their animals, even if traditionally they believe it is safe to do so, as the results could be potentially devastating.”